Rumor is that Romney doesn't want to release his tax returns because he used such aggressive tax avoidance strategies and off shore tax havens to deal with losses in 2008 and 2009 that he paid NO TAXES AT ALL in one if not both of those years or at most he paid only 3% to 5% tax. If that is true, I can understand why he wouldn’t want the American people to know. Rich guy uses tax tricks and off shore accounts to avoid paying taxes while the common guy gets stuck.
Joshua Green at Bloomberg says Romney’s 2009 return might be the biggest problem. “He’s revealed what’s in his 2010 and 2011 returns; and he reportedly submitted 20-some years’ worth of returns to the McCain campaign when he was being vetted for vice president in 2008. Steve Schmidt, McCain’s chief strategist in that campaign, said on MSNBC last night that while he didn’t examine Romney’s returns himself, nothing that McCain’s vetters found in them disqualified Romney from consideration.
That would indicate that 2009 is singularly important and, if there’s anything to this theory, incredibly vexing for Romney because there’s no way he could release additional returns without including that year. And the chaos that would ensue would be bad enough that it’s probably worth enduring significant damage to avoid.”
Read more here: http://www.washingtonpost.com/blogs/ezra-klein/wp/2012/07/17/did-mitt-romney-pay-any-federal-taxes-at-all-in-2009/